1. Field of the Invention
The present invention relates generally to an instrument for aligning optical collimators.
2. Description of the Prior Art
U.S. Pat. No. 6,168,319 disclosed a system and method for aligning an optical fiber collimator. According to this prior art, as shown in FIG. 1, a glass ferrule 91 and a graded-index (GRIN) lens 92 are eventually bonded to the inside of a glass tube 90, and the glass tube is attached to a stationary fixture 95. A small amount of glue, such as a thermally curing epoxy, UV curing epoxy, is injected in the aperture 911 of the glass ferrule 91 and spread between the glass tube 90 and the glass ferrule 91. An optical fiber 912 inserted in the aperture 911 of the glass ferrule 91 is connected with a laser 93 and fixed to a one-dimensional stage 913 providing motion for it and the ferrule 91 along the direction of the cylindrical axis of the glass tube 90 and the optical axis of the grasped fiber 912. During aligning the optical collimator, a detector 96 detects a signal, which travels through the fiber 912 and GRIN lens 92. Thereafter, the position of the ferrule/fiber is adjusted within the tube while the size of the resultant beam is measured at a fixed distance from the output of the GRIN lens by the detector 96. When the detector 96 obtains an optimum beam size, the ferrule 91 is bonded to the glass tube 90 by curing the glue.
However, in the prior art, the ferrule/fiber is merely adjusted by the one-dimensional stage, and moved along the direction of the cylindrical axis of the glass tube. Therefore, the ferrule/fiber cannot be adjusted in other dimension. For example, the ferrule/fiber cannot rotate around the cylindrical axis of the glass tube.
The object of the present invention is to provide an instrument and method for aligning optical collimators precisely, wherein the GRIN lens in the glass tube of each optical collimator is adjusted in two dimensions. The GRIN lens can be moved along the cylindrical axis of the glass tube and rotated around the cylindrical axis of the glass tube.
According to the object of the invention, the instrument for aligning optical collimators includes a frame base, a clamp, a first axis stage, a second axis stage and a rack. A ferrule grasping a fiber therein is inserted into a glass tube, and then the glass tube is fixed to the frame base by the clamp. A pinion is mounted on a GRIN lens, which is inserted in the glass tube, and engaged with the rack. The two stages respectively adjust the GRIN lens to align with the ferrule, wherein the first axis stage moves the GRIN lens along the cylindrical axis of the glass tube and the second axis stage rotates the GRIN lens around the cylindrical axis of the glass tube.
The invention has an advantage of precisely aligning the GRIN lens with the fiber held in the ferrule by adjusting the GRIN lens in two dimensions.
The invention has another advantage of increasing yield rate and productivity.